FIG. 7 of the accompanying drawings shows an air-conditioning system comprising a combination of an absorption heat pump (200: represented by HP) as a heat source and an air-conditioning unit employing a desiccant, i.e., a so-called desiccant air-conditioning unit.
The air-conditioning system comprises an air-conditioning unit having a path A for processing air from which moisture has been adsorbed by a desiccant wheel 103, a path B for regenerating air which is heated by a heat source and thereafter passes through the desiccant wheel 103 that has adsorbed the moisture to desorb the moisture from the desiccant, and an air-conditioning unit having a sensible heat exchanger 104 between the processing air from which moisture has been adsorbed and the regenerating air to be regenerated by the desiccant wheel 103 and heated by the heat source,and an absorption heat pump 200. The regenerating air of the air-conditioning unit is heated by a heater 120 using the high temperature heat source of the absorption heat pump 200 as a heating source, for thereby regenerating the desiccant, and the processing air of the air-conditioning unit is cooled by a cooler 115 using the low temperature heat source of the absorption heat pump as a cooling heat source.
The air-conditioning system is arranged such that the absorption heat pump simultaneously cools the processing air and heats the regenerating air of the desiccant air-conditioning unit. Based on drive heat applied to the absorption heat pump from an external source, the absorption heat pump produces an effect of cooling the processing air. The desiccant is regenerated by the sum of the heat removed from the processing air by the operation of the heat pump and the drive heat applied to the absorption heat pump. Therefore, the drive energy applied from the external source is utilized in multiple ways for a high energy-saving effect.
In this air-conditioning system, as can be seen from an air cycle shown in the psychromretric chart shown in, FIG. 8 of the accompanying drawings, the cooling effect of a so-called desiccant cooling cycle, which is a cooling affect (.DELTA.Q-.DELTA.q) obtained as a result of a quantity of heat (.DELTA.H) applied to the regenerating air to regenerate the desiccant, is greater as the temperature of outside air (state Q) which exchanges heat with the processing air (state L) after the moisture has been adsorbed therefrom is lower. Therefore, as a means for increasing the cooling effect of the entire system, a system of cooling air for cooling the processing air of the state L may be provided separately from the system of the processing air. In this case, the cooling air is previously humidified to lower its temperature and exchanged heat with the processing air for thereby increasing the cooling effect.
An example in which the separate system of cooling air is added is shown in FIG. 9 of the accompanying drawings, and state changes of air in the example shown in FIG. 9 are shown in the psychrometric chart shown in FIG. 10 of the accompanying drawings.
The example shown in FIG. 9 differs from the system shown in FIG. 7 in that the regenerating air.(system B) is not used as the heat exchange medium of the sensible heat exchanger 104 which exchanges heat with the processing air (system A) from which moisture has been adsorbed by the desiccant wheel 104, but another system C of cooling air is provided, and outside air (OA) is introduced into the system C and humidified and cooled by a humidifier 165 into cooling air, which is used as the heat exchange medium of the sensible heat exchanger 104 to cool the processing air. With this arrangement, as shown in FIG. 10, the temperatures of the cooling air (state D) at an inlet of the sensible heat exchanger 104 is lowered by humidification, and the, flow rate of the cooling air can be increased. Therefore, the heat capacity of the cooling air is increased, and the temperature of the cooled processing air (state M) is made lower than the temperature in the system shown in FIG. 7, resulting in an increased cooling effect.
In the above air-conditioning system, however, for an air-conditioning load with a sensible heat factor, i.e., when the temperature is relatively low and the humidity is high as in a rainy season, the amount of heating by the heat pump to regenerate the desiccant to be dehumidified and the amount of cooling for processing the sensible heat of air are placed out of balance. If priority is given to dehumidification, then the amount of cooling by the low temperature heat source 115 of the heat pump becomes excessive, and the temperature of air supplied from the air-conditioning unit is lowered to excessively cool the air-conditioned space.
The present invention has been made in view of the above drawbacks. It is an object of the present invention to suppress the quantity of heat for cooling processing air as a low temperature heat source for regenerating a desiccant to be dehumidified, by a sensible heat exchanger before reaching a low temperature heat source heat exchanger, for thereby maintaining a heat load on the low temperature heat source heat exchanger and making it possible to handle an air-conditioning load with a small sensible heat factor.